Math Trig
posted by kyu .
Suppose that X is an angle in standard position and that X' is it's reference angle. If cosX = 4/ squareroot of 17. find the exact value of cosX'
is it 4/square root of 17?

Math Trig 
Reiny
yes, X' would be in quadrant I, so its cosine would be positive.
cos X' = 4/√17
Respond to this Question
Similar Questions

Math
Verify the identity . (cscXcotX)^2=1cosX/1+cosX _______ sorry i cant help you (cscXcotX)=1/sinX  cosX/sinX = (1cosX)/sinX If you square this you have (1cosX)^2/(sinX)^2 Now use (sinX)^2 = 1  (cosX)^2 to get (1cosX)^2 / 1  … 
MATH PLEASE
can a reference angle be negative? Tye "reference angle" in google and check out the mathwords site :) no I copied and pasted the mathwords page for you, unfortunatly the diagram that was with it cant, express itself in text so it 
Trig........
I need to prove that the following is true. Thanks (cosx / 1sinx ) = ( 1+sinx / cosx ) I recall this question causing all kinds of problems when I was still teaching. it requires a little "trick" L.S. =cosx/(1sinx) multiply top and … 
Trig
Find the exact value of sinx/2 if cosx = 2/3 and 270 < x < 360. A)1/3 B)1/3 C)sqrt 6/6 D)sqrt 6/6 C, since I KNOW cosx is always positive but I don't know the work involved. I know the half angle formula 
trig
Angle x is in the second quadrant and angle y is in the first quadrant such that sinx=5/13 and cosy=3/5. a) Determine an exact value for cosx b) Determine an exact value for siny 
trig
Angle x is in the second quadrant and angle y is in the first quadrant such that sinx=5/13 and cosy=3/5. a) Determine an exact value for cosx b) Determine an exact value for siny 
Trig
I'm confused on how to determine what the end result angles are for a trigonometric identity (I get how to find the value of sin, cos, etc., and I know how to find the reference angle. I just don't know how to determine further angles … 
mathtrig
Use the double angle identities to find sin2x if sinx= 1/square of 17 and cosx<0 . Give exact answer. 
trig
(a) sketch an angle A in standard position whose terminal ray passses through the point (1,4) (b) Find the exact value of the six trigonometric functions of A, (c) Let B be the reference angle of A. Find a point on the terminal rsy … 
MATH: TRIG
IF X IS AN ANGLE IN THE FIRST QUADRANT AND COSX= 3/5, FIND THE EXACT VALUE OF SIN2X DONT UNDERSTAND, KNOW THAT THE COSX IS ON A 3,4,5 TRIANGLE